1. Field of the Invention
The invention relates to noise control in suspended ceilings. Such suspended ceilings have a grid of intersecting metal beams that are suspended by hangers from a structural ceiling. Panels or drywall sheets are supported on the grid.
Noise generated in the structural ceiling, which is frequently a floor for the space above, is transmitted by sound vibrations passing downward through the hangers, which form a sound path, to the grid of the suspended ceiling. The suspended ceiling, which includes panels or drywall sheets attached to the beams in the grid, forms a receiver for the sound vibrations, which broadcasts the resulting unwanted noise to the space below.
The invention deals with deadening such sound vibrations coming down the hangers.
2. Prior Art
Suspended ceilings are constructed in a special way so that the ceilings are extremely stable. Over many years, a standard way of constructing such ceilings has evolved. Suspended ceilings are constructed at a building site by individually embedding an anchor, such as an eye bolt, into the structural ceiling, and then attaching a hanger, such as a wire, to the anchor, by twisting the wire about the anchor. The anchor is secured explosively, or by any other means, such as bolting into the structural ceiling. The lower end of the hanger is attached to a metal beam in a grid that supports panels, or drywall sheets, by looping the hanger through a hole in the web of the beam and twisting the loop closed around the bulb and a segment of the beam.
The substantial weight of the suspended ceiling is spread among numerous hangers that are spaced every few feet along the main beams in the grid. Each hanger must be individually secured to the structural ceiling, and to the grid beam, by an installer who must keep the grid of interconnected main and cross beams level at a desired height. Much time and effort is required to hang a suspended ceiling grid from a structural ceiling.
Much more time and effort is required where sound attenuator devices that dampen the vibrations coming down a hanger sound path, from noise generated in a structural ceiling, are used.
In the prior art, to control noise in a suspended ceiling, a noise attenuator is individually inserted by the installer, about midway in the length of a wire hanger that is cut into two segments. An upper segment of the wire hanger is first secured at its top to the structural ceiling, and at its bottom, to a top terminal in the attenuator. A lower segment of the wire hanger is connected at the top to a bottom terminal in the attenuator, and then, at the bottom of the lower segment, to the grid beam.
In such prior art attenuator, the upper and lower metal terminals are separated from each other by a suitable amount of sound vibration damping material, such as gum rubber. Sound vibrations coming down the wire hanger sound path from the structural ceiling, which frequently serves as a floor for the building level above, are absorbed in the noise attenuator.
The insertion of such prior art noise attenuators in a wire hanger that must be divided into two segments is time and labor consuming, since the normally single segment of a wire hanger must not only be divided into two segments, but each segment must then be secured to the noise attenuator by passing the hanger through an attenuator terminal, and then twisting the hanger back around the segment. Thus, instead of just two attachments of a single segment of a wire hanger at an upper end to the structural ceiling, and at its lower end to a grid beam itself, as in prior art suspended ceilings with no noise attenuation, there are two additional attachments involving threading the wire hanger through a hole, and then twisting the wire hanger back upon itself, to the noise attenuator.
Such manual cutting, threading, and twisting must be individually custom performed by the installer of the grid in the field during the construction of the ceiling, since good judgment must be exerted at each wire hanger to keep the grid level, through controlling the length of the wire hanger suspensions.